A lens problem solved; Land Rover’s new seats; walking with robots; eye tests for Africa; K-Way suit to tackle Everest; Mielie Mailer.

IT’S AN ISSUE that has plagued photography since its creation: blurring, even when everything is in focus. No matter how highquality the camera is, maths has dictated that the curve of spherical lenses means that rays of light coming through won’t converge on the exact same spot. At least, that was the problem until Rafael G González-Acuña, a doctoral student at Mexico’s Tecnológico de Monterrey, up and solved it.

The problem goes back thousands of years to the Greek mathematician Diocles. A contemporary of Archimedes, Diocles wrote a book that was titled On Burning Mirrors, in which he describes what would become known as a ‘spherical aberration’. As light rays fall on a lens, different rays don’t meet in a single focal point. Even the most high-end lenses can’t totally remove the aberration. Since Diocles brought up the problem, nobody in history had been able to find a good answer. And considering the massive uptick in camera ownership over the last

two decades, in the form of billions of smartphones, that’s saying something.

But Héctor A Chaparro-Romo, a doctoral student at the National Autonomous University of Mexico (UNAM), had a feeling that the problem could be solved. He began working on a solution three years ago, and later invited González-Acuña to work with him. ‘I remember one morning I was making myself a slice of bread with Nutella, when suddenly,

I said out loud: “Mothers! It is there!”’ González-Acuña said in a recent interview with PetaPixel.

How did he crack the aberration? By using a complex mathematical formula, published in an article entitled ‘General Formula for Bi-Aspheric Singlet Lens Design Free of Spherical Aberration’ in the journal Applied Optics. ‘In this equation we describe how the shape of the second aspherical surface of the given lens should be given a first surface, which is provided by the user, as well as the object-image distance,’ González-Acuña said.

‘The second surface is such that it corrects all the aberration generated by the first surface, and the spherical aberration is eliminated.’

González-Acuña’s formula has serious real-world potential. Apart from providing direction for manufacturers to produce optimised lenses on consumer products, it could make for sharper lenses on scientific equipment, from telescopes to microscopes.

Light passing through into a camera’s lenses never meets at exactly one point, causing blur like this.

Figure 1: The path of light through a typical lens. Spherical aberration prevents it from converging on a single point. Figure 2: Without aberration, light would converge on a focal point, eliminating blur.